The present invention is related to pattern bonded nonwoven fabrics or webs, and the process of producing the same.
Many processes for producing bonded nonwoven fabrics are known in the art. In particular, it is known to apply heat and pressure for bonding at limited areas of a nonwoven web by passing it through the nip between heated calender rolls either or both of which may have patterns of lands and depressions on their surfaces. During such a bonding process, depending on the types of fibers making up the nonwoven web, the bonded regions may be formed autogenously, i.e., the fibers of the web are melt fused at least in the pattern areas, or with the addition of an adhesive.
It is known in the art that physical properties of bonded nonwoven fabrics are related to the degree and the pattern of bonding. In general, a large bonded area may be applied to provide dimensional stability to nonwoven fabrics, at the expense of flexibility and porosity, and geometrically repeating bond patterns are employed to provide isotropic dimensional stability. However, different property requirements for different uses may dictate the use of random or irregular patterns.
It is also known in the art that repeating bond patterns may be altered to produce aesthetically improved nonwoven fabrics. Such attempts are disclosed, for example, in U.S. Pat. Nos. 3,542,634 to J. Such et al.; 4,170,680 to Cumbers and 4,451,520 to Tecl et al. However, these patents do not recognize that properly arranged bond patterns may provide other useful utilities than aesthetical effects.